Polarization sensitive optical diffuser

ABSTRACT

An optical diffuser includes optically anisotropic molecules arranged in a predefined configuration such that the optical diffuser diffuses first light having a first polarization and transmits second light having a second polarization that is different from the first polarization upon receiving the second light. In addition to polarization selectivity, the optical diffuser may also exhibit wavelength selectivity and/or incident angle selectivity. A method of diffusing light using the optical diffuser and a method of making the optical diffuser are also disclosed.

RELATED APPLICATIONS

This application claims the benefit of, and priority to, U.S.Provisional Patent Application Ser. No. 62/902,823, filed Sep. 19, 2019and U.S. Provisional Patent Application Ser. No. 62/902,831, filed Sep.19, 2019, each of which is incorporated by reference herein in itsentirety.

This application is related to U.S. patent application Ser. No.16/714,441, entitled “Varifocal Polarization Sensitive DiffusiveDisplay,” filed Dec. 13, 2019, which claims priority to U.S. ProvisionalPatent Application Ser. No. 62/902,831, filed Sep. 19, 2019 and U.S.Provisional Patent Application Ser. No. 62/902,823, filed Sep. 19, 2019,each of which is incorporated by reference herein in their entireties.

TECHNICAL FIELD

This relates generally to display devices, and more specifically tohead-mounted display devices.

BACKGROUND

Head-mounted display devices (also called herein head-mounted displays)are gaining popularity as means for providing visual information to auser. For example, head-mounted display devices are used for virtualreality and augmented reality (AR) operations.

When using head-mounted display devices in AR applications, it isimportant for the head-mounted display devices to be capable of creatingcohesive AR scenes by seamlessly transmitting ambient light to a user'seyes while projecting images to the user's eyes.

SUMMARY

Accordingly, there is a need for a head-mounted display device that cantransmit both ambient light and project image light to a user's eyes.Certain embodiments of the present disclosure provide optical diffusersthat are configurable to transmit ambient light and diffuse image light.In some embodiments, the ambient light is transmitted to the userwithout significant aberrations or distortions. Thus, the opticaldiffusers is suitable for use in head-mounted displays to facilitate ARapplications.

Thus, the above deficiencies and other problems associated withhead-mounted displays are reduced or eliminated by the disclosed opticaldiffusers.

In accordance with some embodiments, an optical diffuser includesoptically anisotropic molecules arranged in a predefined configurationsuch that the optical diffuser outputs diffuse light upon receivingfirst light having a first polarization, and transmits second lighthaving a second polarization that is different from the firstpolarization upon receiving the second light.

In accordance with some embodiments, an optical diffuser includes afirst surface, a second surface opposite to the first surface, andoptically anisotropic molecules disposed between the first surface andthe second surface. The optically anisotropic molecules are arrangedsuch that the optical diffuser outputs diffuse light upon receivingfirst light having a first polarization, and transmits second lighthaving a second polarization that is different from the firstpolarization.

In accordance with some embodiments, a method of diffusing lightincludes receiving incident light at an optical diffuser that includesoptically anisotropic molecules arranged in a predefined configurationand outputting diffuse light from the optical diffuser on response toreceiving the incident light when the incident light has a first set ofproperties. The first set of properties includes a first polarization.The method also includes transmitting the incident light in response toreceiving the incident light when the incident light has a second set ofproperties. The second set of properties includes a second polarizationthat is different from the first polarization

In accordance with some embodiments, a method of diffusing lightincludes receiving incident light at a first surface and outputtingdiffuse light from the first surface or a second surface. Outputtingdiffuse light includes allowing the incident light to interact withoptically anisotropic molecules disposed between the first surface andthe second surface. The optically anisotropic molecules are arrangedsuch that light having a first set of properties, including a firstpolarization, is diffused by the optically anisotropic molecules andlight having a second set of properties, including a second polarizationthat is different from the first polarization, is transmitted throughthe optically anisotropic molecules.

In accordance with some embodiments, a method of making an opticaldiffuser includes illuminating optically anisotropic molecules withdirectional light having a first polarization and, concurrently withilluminating the optically anisotropic molecules with the directionallight, illuminating the optically anisotropic molecules with diffuselight having a second polarization that is different from the firstpolarization.

Thus, the disclosed embodiments provide a polarization selective opticaldiffuser that is capable of diffusing image light having a firstpolarization and transmitting ambient light that has a polarizationdifferent from the first polarization without diffusing the ambientlight and without adding significant aberration or distortion to theambient light.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the various described embodiments,reference should be made to the Description of Embodiments below, inconjunction with the following drawings in which like reference numeralsrefer to corresponding parts throughout the figures.

FIG. 1 is a perspective view of a display device in accordance with someembodiments.

FIG. 2 is a block diagram of a system including a display device inaccordance with some embodiments.

FIG. 3 is an isometric view of a display device in accordance with someembodiments.

FIG. 4A is a cross-sectional diagram of a polarization sensitive opticaldiffuser in accordance with some embodiments.

FIG. 4B is a cross-sectional diagram of a transmissive polarizationsensitive optical diffuser in accordance with some embodiments.

FIG. 4C is a cross-sectional diagram of a reflective polarizationsensitive optical diffuser in accordance with some embodiments.

FIG. 4D is a schematic diagram illustrating incident angle selectivityof a polarization sensitive optical diffuser in accordance with someembodiments.

FIG. 4E is a schematic diagram illustrating wavelength selectivity of apolarization sensitive optical diffuser in accordance with someembodiments.

FIG. 5 is a schematic diagram illustrating the optical path of lighttransmitted through a polarization sensitive optical diffuser inaccordance with some embodiments.

FIGS. 6A-6C are schematic diagrams illustrating a polarization sensitiveoptical diffuser in accordance with some embodiments.

FIG. 7 is a flowchart illustrating a method of diffusing light inaccordance with some embodiments.

FIG. 8 is a flowchart illustrating a method of creating a polarizationsensitive optical diffuser in accordance with some embodiments.

FIG. 9 is a schematic diagram illustrating a polarization sensitiveoptical diffuser according to some embodiments.

These figures are not drawn to scale unless indicated otherwise.

DETAILED DESCRIPTION

The present disclosure provides a polarization sensitive opticaldiffuser that diffuses first light having a first polarization andtransmits second light, having a second polarization, without diffusingthe second light. In some embodiments, the second light is transmittedwithout a change in direction and polarization.

Reference will now be made to embodiments, examples of which areillustrated in the accompanying drawings. In the following description,numerous specific details are set forth in order to provide anunderstanding of the various described embodiments. However, it will beapparent to one of ordinary skill in the art that the various describedembodiments may be practiced without these specific details. In otherinstances, well-known methods, procedures, components, circuits, andnetworks have not been described in detail so as not to unnecessarilyobscure aspects of the embodiments.

It will also be understood that, although the terms first, second, etc.are, in some instances, used herein to describe various elements, theseelements should not be limited by these terms. These terms are used onlyto distinguish one element from another. For example, a first lightprojector could be termed a second light projector, and, similarly, asecond light projector could be termed a first light projector, withoutdeparting from the scope of the various described embodiments. The firstlight projector and the second light projector are both lightprojectors, but they are not the same light projector.

The terminology used in the description of the various describedembodiments herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used in thedescription of the various described embodiments and the appendedclaims, the singular forms “a,” “an,” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will also be understood that the term “and/or” as usedherein refers to and encompasses any and all possible combinations ofone or more of the associated listed items. It will be furtherunderstood that the terms “includes,” “including,” “comprises,” and/or“comprising,” when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof. The term “exemplary” is used herein in the senseof “serving as an example, instance, or illustration” and not in thesense of “representing the best of its kind.”

FIG. 1 illustrates a perspective view of display device 100 inaccordance with some embodiments. In some embodiments, display device100 is configured to be worn on a head of a user (e.g., by having theform of spectacles or eyeglasses, as shown in FIG. 1, or to be includedas part of a helmet that is to be worn by the user). When display device100 is configured to be worn on a head of a user, display device 100 iscalled a head-mounted display. Alternatively, display device 100 isconfigured for placement in proximity of an eye or eyes of the user at afixed location, without being head-mounted (e.g., display device 100 ismounted in a vehicle, such as a car or an airplane, for placement infront of an eye or eyes of the user). As shown in FIG. 1, display device100 includes display 110. Display 110 is configured for presentingvisual contents (e.g., augmented reality contents, virtual realitycontents, mixed-reality contents, or any combination thereof) to a user.

In some embodiments, display device 100 includes one or more componentsdescribed herein with respect to FIG. 2. In some embodiments, displaydevice 100 includes additional components not shown in FIG. 2.

FIG. 2 is a block diagram of system 200 in accordance with someembodiments. The system 200 shown in FIG. 2 includes display device 205(which corresponds to display device 100 shown in FIG. 1), imagingdevice 235, and input interface 240 that are each coupled to console210. While FIG. 2 shows an example of system 200 including displaydevice 205, imaging device 235, and input interface 240, in otherembodiments, any number of these components may be included in system200. For example, there may be multiple display devices 205 each havingassociated input interface 240 and being monitored by one or moreimaging devices 235, with each display device 205, input interface 240,and imaging devices 235 communicating with console 210. In alternativeconfigurations, different and/or additional components may be includedin system 200. For example, in some embodiments, console 210 isconnected via a network (e.g., the Internet) to system 200 or isself-contained as part of display device 205 (e.g., physically locatedinside display device 205). In some embodiments, display device 205 isused to create mixed-reality by adding in a view of the realsurroundings. Thus, display device 205 and system 200 described here candeliver augmented reality, virtual reality, and mixed-reality.

In some embodiments, as shown in FIG. 1, display device 205 is ahead-mounted display that presents media to a user. Examples of mediapresented by display device 205 include one or more images, video,audio, or some combination thereof. In some embodiments, audio ispresented via an external device (e.g., speakers and/or headphones) thatreceives audio information from display device 205, console 210, orboth, and presents audio data based on the audio information. In someembodiments, display device 205 immerses a user in an augmentedenvironment.

In some embodiments, display device 205 also acts as an augmentedreality (AR) headset. In these embodiments, display device 205 augmentsviews of a physical, real-world environment with computer-generatedelements (e.g., images, video, sound, etc.). Moreover, in someembodiments, display device 205 is able to cycle between different typesof operation. Thus, display device 205 operate as a virtual reality (VR)device, an augmented reality (AR) device, as glasses or some combinationthereof (e.g., glasses with no optical correction, glasses opticallycorrected for the user, sunglasses, or some combination thereof) basedon instructions from application engine 255.

Display device 205 includes electronic display 215, one or moreprocessors 216, eye tracking module 217, adjustment module 218, one ormore locators 220, one or more position sensors 225, one or moreposition cameras 222, memory 228, inertial measurement unit (IMU) 230,one or more optical assemblies 260, or a subset or superset thereof(e.g., display device 205 with electronic display 215, optical assembly260, without any other listed components). Some embodiments of displaydevice 205 have different modules than those described here. Similarly,the functions can be distributed among the modules in a different mannerthan is described here.

One or more processors 216 (e.g., processing units or cores) executeinstructions stored in memory 228. Memory 228 includes high-speed randomaccess memory, such as DRAM, SRAM, DDR RAM or other random access solidstate memory devices; and may include non-volatile memory, such as oneor more magnetic disk storage devices, optical disk storage devices,flash memory devices, or other non-volatile solid state storage devices.Memory 228, or alternately the non-volatile memory device(s) withinmemory 228, includes a non-transitory computer readable storage medium.In some embodiments, memory 228 or the computer readable storage mediumof memory 228 stores programs, modules and data structures, and/orinstructions for displaying one or more images on electronic display215.

Electronic display 215 displays images to the user in accordance withdata received from console 210 and/or processor(s) 216. In variousembodiments, electronic display 215 may comprise a single adjustabledisplay element or multiple adjustable display elements (e.g., a displayfor each eye of a user). In some embodiments, electronic display 215 isconfigured to project images to the user through one or more opticalassemblies 260.

In some embodiments, the display element includes one or more lightemission devices and a corresponding array of spatial light modulators.A spatial light modulator is an array of electro-optic pixels,opto-electronic pixels, some other array of devices that dynamicallyadjust the amount of light transmitted by each device, or somecombination thereof. These pixels are placed behind one or more lenses.In some embodiments, the spatial light modulator is an array of liquidcrystal based pixels in an LCD (a Liquid Crystal Display). Examples ofthe light emission devices include: an organic light emitting diode, anactive-matrix organic light-emitting diode, a light emitting diode, sometype of device capable of being placed in a flexible display, or somecombination thereof. The light emission devices include devices that arecapable of generating visible light (e.g., red, green, blue, etc.) usedfor image generation. The spatial light modulator is configured toselectively attenuate individual light emission devices, groups of lightemission devices, or some combination thereof. Alternatively, when thelight emission devices are configured to selectively attenuateindividual emission devices and/or groups of light emission devices, thedisplay element includes an array of such light emission devices withouta separate emission intensity array.

One or more optical components in the one or more optical assemblies 260direct light from the arrays of light emission devices (optionallythrough the emission intensity arrays) to locations within each eyebox.An eyebox is a region that is occupied by an eye of a user of displaydevice 205 (e.g., a user wearing display device 205) who is viewingimages from display device 205. In some embodiments, the eyebox isrepresented as a 10 mm×10 mm square. In some embodiments, the one ormore optical components include one or more coatings, such asanti-reflective coatings.

In some embodiments, the display element includes an infrared (IR)detector array that detects IR light that is retro-reflected from theretinas of a viewing user, from the surface of the corneas, lenses ofthe eyes, or some combination thereof. The IR detector array includes anIR sensor or a plurality of IR sensors that each correspond to adifferent position of a pupil of the viewing user's eye. In alternateembodiments, other eye tracking systems may also be employed.

Eye tracking module 217 determines locations of each pupil of a user'seyes. In some embodiments, eye tracking module 217 instructs electronicdisplay 215 to illuminate the eyebox with IR light (e.g., via IRemission devices in the display element).

A portion of the emitted IR light will pass through the viewing user'spupil and be retro-reflected from the retina toward the IR detectorarray, which is used for determining the location of the pupil.Alternatively, the reflection off of the surfaces of the eye is used toalso determine location of the pupil. The IR detector array scans forretro-reflection and identifies which IR emission devices are activewhen retro-reflection is detected. Eye tracking module 217 may use atracking lookup table and the identified IR emission devices todetermine the pupil locations for each eye. The tracking lookup tablemaps received signals on the IR detector array to locations(corresponding to pupil locations) in each eyebox. In some embodiments,the tracking lookup table is generated via a calibration procedure(e.g., user looks at various known reference points in an image and eyetracking module 217 maps the locations of the user's pupil while lookingat the reference points to corresponding signals received on the IRtracking array). As mentioned above, in some embodiments, system 200 mayuse other eye tracking systems than the embedded IR one describedherein.

Adjustment module 218 generates an image frame based on the determinedlocations of the pupils. In some embodiments, this sends a discreteimage to the display that will tile sub-images together thus a coherentstitched image will appear on the back of the retina. Adjustment module218 adjusts an output (i.e. the generated image frame) of electronicdisplay 215 based on the detected locations of the pupils. Adjustmentmodule 218 instructs portions of electronic display 215 to pass imagelight to the determined locations of the pupils. In some embodiments,adjustment module 218 also instructs the electronic display to not passimage light to positions other than the determined locations of thepupils. Adjustment module 218 may, for example, block and/or stop lightemission devices whose image light falls outside of the determined pupillocations, allow other light emission devices to emit image light thatfalls within the determined pupil locations, translate and/or rotate oneor more display elements, dynamically adjust curvature and/or refractivepower of one or more active lenses in the lens (e.g., microlens) arrays,or some combination thereof.

Optional locators 220 are objects located in specific positions ondisplay device 205 relative to one another and relative to a specificreference point on display device 205. A locator 220 may be a lightemitting diode (LED), a corner cube reflector, a reflective marker, atype of light source that contrasts with an environment in which displaydevice 205 operates, or some combination thereof. In embodiments wherelocators 220 are active (i.e., an LED or other type of light emittingdevice), locators 220 may emit light in the visible band (e.g., about400 nm to 750 nm), in the infrared band (e.g., about 750 nm to 1 mm), inthe ultraviolet band (about 100 nm to 400 nm), some other portion of theelectromagnetic spectrum, or some combination thereof.

In some embodiments, locators 220 are located beneath an outer surfaceof display device 205, which is transparent to the wavelengths of lightemitted or reflected by locators 220 or is thin enough to notsubstantially attenuate the light emitted or reflected by locators 220.Additionally, in some embodiments, the outer surface or other portionsof display device 205 are opaque in the visible band of wavelengths oflight. Thus, locators 220 may emit light in the IR band under an outersurface that is transparent in the IR band but opaque in the visibleband.

IMU 230 is an electronic device that generates calibration data based onmeasurement signals received from one or more position sensors 225.Position sensor 225 generates one or more measurement signals inresponse to motion of display device 205. Examples of position sensors225 include: one or more accelerometers, one or more gyroscopes, one ormore magnetometers, another suitable type of sensor that detects motion,a type of sensor used for error correction of IMU 230, or somecombination thereof. Position sensors 225 may be located external to IMU230, internal to IMU 230, or some combination thereof.

Based on the one or more measurement signals from one or more positionsensors 225, IMU 230 generates first calibration data indicating anestimated position of display device 205 relative to an initial positionof display device 205. For example, position sensors 225 includemultiple accelerometers to measure translational motion (forward/back,up/down, left/right) and multiple gyroscopes to measure rotationalmotion (e.g., pitch, yaw, roll). In some embodiments, IMU 230 rapidlysamples the measurement signals and calculates the estimated position ofdisplay device 205 from the sampled data. For example, IMU 230integrates the measurement signals received from the accelerometers overtime to estimate a velocity vector and integrates the velocity vectorover time to determine an estimated position of a reference point ondisplay device 205. Alternatively, IMU 230 provides the sampledmeasurement signals to console 210, which determines the firstcalibration data. The reference point is a point that may be used todescribe the position of display device 205. While the reference pointmay generally be defined as a point in space; however, in practice thereference point is defined as a point within display device 205 (e.g., acenter of IMU 230).

In some embodiments, IMU 230 receives one or more calibration parametersfrom console 210. As further discussed below, the one or morecalibration parameters are used to maintain tracking of display device205. Based on a received calibration parameter, IMU 230 may adjust oneor more IMU parameters (e.g., sample rate). In some embodiments, certaincalibration parameters cause IMU 230 to update an initial position ofthe reference point so it corresponds to a next calibrated position ofthe reference point. Updating the initial position of the referencepoint as the next calibrated position of the reference point helpsreduce accumulated error associated with the determined estimatedposition. The accumulated error, also referred to as drift error, causesthe estimated position of the reference point to “drift” away from theactual position of the reference point over time.

Imaging device 235 generates calibration data in accordance withcalibration parameters received from console 210. Calibration dataincludes one or more images showing observed positions of locators 220that are detectable by imaging device 235. In some embodiments, imagingdevice 235 includes one or more still cameras, one or more videocameras, any other device capable of capturing images including one ormore locators 220, or some combination thereof. Additionally, imagingdevice 235 may include one or more filters (e.g., used to increasesignal to noise ratio). Imaging device 235 is configured to optionallydetect light emitted or reflected from locators 220 in a field of viewof imaging device 235. In embodiments where locators 220 include passiveelements (e.g., a retroreflector), imaging device 235 may include alight source that illuminates some or all of locators 220, whichretro-reflect the light toward the light source in imaging device 235.Second calibration data is communicated from imaging device 235 toconsole 210, and imaging device 235 receives one or more calibrationparameters from console 210 to adjust one or more imaging parameters(e.g., focal length, focus, frame rate, ISO, sensor temperature, shutterspeed, aperture, etc.).

In some embodiments, display device 205 includes one or more opticalassemblies 260, which can include a single optical assembly 260 ormultiple optical assemblies 260 (e.g., an optical assembly 260 for eacheye of a user). In some embodiments, the one or more optical assemblies260 receive image light for the computer generated images from theelectronic display 215 and direct the image light toward an eye or eyesof a user. The computer-generated images include still images, animatedimages, and/or a combination thereof. The computer-generated imagesinclude objects that appear to be two-dimensional and/orthree-dimensional objects.

In some embodiments, electronic display 215 projects computer-generatedimages to one or more reflective elements (not shown), and the one ormore optical assemblies 260 receive the image light from the one or morereflective elements and direct the image light to the eye(s) of theuser. In some embodiments, the one or more reflective elements arepartially transparent (e.g., the one or more reflective elements have atransmittance of at least 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%),which allows transmission of ambient light. In such embodiments,computer-generated images projected by electronic display 215 aresuperimposed with the transmitted ambient light (e.g., transmittedambient image) to provide augmented reality images.

Input interface 240 is a device that allows a user to send actionrequests to console 210. An action request is a request to perform aparticular action. For example, an action request may be to start or endan application or to perform a particular action within the application.Input interface 240 may include one or more input devices. Example inputdevices include: a keyboard, a mouse, a game controller, data from brainsignals, data from other parts of the human body, or any other suitabledevice for receiving action requests and communicating the receivedaction requests to console 210. An action request received by inputinterface 240 is communicated to console 210, which performs an actioncorresponding to the action request. In some embodiments, inputinterface 240 may provide haptic feedback to the user in accordance withinstructions received from console 210. For example, haptic feedback isprovided when an action request is received, or console 210 communicatesinstructions to input interface 240 causing input interface 240 togenerate haptic feedback when console 210 performs an action.

Console 210 provides media to display device 205 for presentation to theuser in accordance with information received from one or more of:imaging device 235, display device 205, and input interface 240. In theexample shown in FIG. 2, console 210 includes application store 245,tracking module 250, and application engine 255. Some embodiments ofconsole 210 have different modules than those described in conjunctionwith FIG. 2. Similarly, the functions further described herein may bedistributed among components of console 210 in a different manner thanis described here.

When application store 245 is included in console 210, application store245 stores one or more applications for execution by console 210. Anapplication is a group of instructions, that when executed by aprocessor, is used for generating content for presentation to the user.Content generated by the processor based on an application may be inresponse to inputs received from the user via movement of display device205 or input interface 240. Examples of applications include: gamingapplications, conferencing applications, video playback application, orother suitable applications.

When tracking module 250 is included in console 210, tracking module 250calibrates system 200 using one or more calibration parameters and mayadjust one or more calibration parameters to reduce error indetermination of the position of display device 205. For example,tracking module 250 adjusts the focus of imaging device 235 to obtain amore accurate position for observed locators on display device 205.Moreover, calibration performed by tracking module 250 also accounts forinformation received from IMU 230. Additionally, if tracking of displaydevice 205 is lost (e.g., imaging device 235 loses line of sight of atleast a threshold number of locators 220), tracking module 250re-calibrates some or all of system 200.

In some embodiments, tracking module 250 tracks movements of displaydevice 205 using second calibration data from imaging device 235. Forexample, tracking module 250 determines positions of a reference pointof display device 205 using observed locators from the secondcalibration data and a model of display device 205. In some embodiments,tracking module 250 also determines positions of a reference point ofdisplay device 205 using position information from the first calibrationdata. Additionally, in some embodiments, tracking module 250 may useportions of the first calibration data, the second calibration data, orsome combination thereof, to predict a future location of display device205. Tracking module 250 provides the estimated or predicted futureposition of display device 205 to application engine 255.

Application engine 255 executes applications within system 200 andreceives position information, acceleration information, velocityinformation, predicted future positions, or some combination thereof ofdisplay device 205 from tracking module 250. Based on the receivedinformation, application engine 255 determines content to provide todisplay device 205 for presentation to the user. For example, if thereceived information indicates that the user has looked to the left,application engine 255 generates content for display device 205 thatmirrors the user's movement in an augmented environment. Additionally,application engine 255 performs an action within an applicationexecuting on console 210 in response to an action request received frominput interface 240 and provides feedback to the user that the actionwas performed. The provided feedback may be visual or audible feedbackvia display device 205 or haptic feedback via input interface 240.

FIG. 3 is an isometric view of a display device 300, which correspondsto part of or all of display device 100 (see FIG. 1) in accordance withsome embodiments. In some embodiments, display device 300 includes alight emission device array 310 (e.g., a light emission device array orreflective element), and an optical assembly (e.g., optical assembly260) having one or more optical components 330 (e.g., lenses). In someembodiments, display device 300 also includes an IR detector array.

In some embodiments, light emission device array 310 emits image lightand optional IR light toward the optical components 330. Light emissiondevice array 310 may be, e.g., an array of LEDs, an array of microLEDs,an array of OLED s, or some combination thereof. Light emission devicearray 310 includes light emission devices 320 that emit light in thevisible light (and optionally includes devices that emit light in theIR).

In some embodiments, display device 300 includes an emission intensityarray configured to selectively attenuate light emitted from lightemission device array 310. In some embodiments, the emission intensityarray is composed of a plurality of liquid crystal cells or pixels,groups of light emission devices, or some combination thereof. Each ofthe liquid crystal cells is, or in some embodiments, groups of liquidcrystal cells are, addressable to have specific levels of attenuation.For example, at a given time, some of the liquid crystal cells may beset to no attenuation, while other liquid crystal cells may be set tomaximum attenuation. In this manner, the emission intensity array isable to control what portion of the image light emitted from lightemission device array 310 is passed to the one or more opticalcomponents 330. In some embodiments, display device 300 uses an emissionintensity array to facilitate providing image light to a location ofpupil 350 of eye 340 of a user, and minimize the amount of image lightprovided to other areas in the eyebox.

An optional IR detector array detects IR light that has beenretro-reflected from the retina of eye 340, a cornea of eye 340, acrystalline lens of eye 340, or some combination thereof. The IRdetector array includes either a single IR sensor or a plurality of IRsensitive detectors (e.g., photodiodes). In some embodiments, the IRdetector array is separate from light emission device array 310. In someembodiments, the IR detector array is integrated into light emissiondevice array 310.

In some embodiments, light emission device array 310 and an emissionintensity array make up a display element. Alternatively, the displayelement includes light emission device array 310 (e.g., when lightemission device array 310 includes individually adjustable pixels)without the emission intensity array. In some embodiments, the displayelement additionally includes the IR array. In some embodiments, inresponse to a determined location of pupil 350, the display elementadjusts the emitted image light such that the light output by thedisplay element is refracted by one or more optical components 330toward the determined location of pupil 350, and not toward anotherpresumed location.

In some embodiments, display device 300 includes one or more broadbandsources (e.g., one or more white LEDs) coupled with a plurality of colorfilters, in addition to, or instead of, light emission device array 310.

One or more optical components 330 receive the image light (or modifiedimage light, e.g., attenuated light) from light emission device array310, and direct the image light to a detected or presumed location ofthe pupil 350 of an eye 340 of a user. In some embodiments, the one ormore optical components include one or more optical assemblies 260.

FIG. 4A is a cross-sectional diagram of a polarization sensitive opticaldiffuser 400 in accordance with some embodiments. Polarization sensitiveoptical diffuser 400 includes a first surface 400-1, a second surface400-2 opposite to first surface 400-1, and optically anisotropicmolecules 409 disposed between the first surface 400-1 and the secondsurface 400-2. Polarization sensitive optical diffuser 400 is configuredto output diffuse light upon receiving first light (e.g., light 410)having first circular polarization (e.g., right-handed circularpolarization or RCP), and to transmit second light (e.g., light 420)having second circular polarization (e.g., left-handed circularpolarization or LCP) that is different from (e.g., orthogonal to) thefirst circular polarization, or vice versa.

Polarization sensitive optical diffuser 400 may be a transmissivepolarization sensitive optical diffuser, such as the transmissivepolarization sensitive optical diffuser 401 shown in FIG. 4B, or areflective polarization sensitive optical diffuser, such as thereflective polarization sensitive optical diffuser 402, shown in FIG.4C.

As shown in FIG. 4B, transmissive polarization sensitive opticaldiffuser 401 includes a first surface 401-1, a second surface 401-2opposite to first surface 401-1, and optically anisotropic moleculesdisposed between the first surface 401-1 and the second surface 401-2.In some embodiments, transmissive polarization sensitive opticaldiffuser 401 is configured to output light from second surface 401-2 inresponse to receiving incident light at first surface 401-1. As shown,when the incident light (e.g., light 410) has the first circularpolarization, diffuse light 412 having the second circular polarizationis output from the second surface 401-2. In some embodiments, light 410is substantially collimated and propagating in a first direction. Insome embodiments, transmissive polarization sensitive optical diffuser401 is configured to diffuse the light 410 so as to output diffuse light412 that propagates in a plurality of directions. When the incidentlight (e.g., light 420) has the second circular polarization,transmissive polarization sensitive optical diffuser 401 is configuredto transmit the light 420. Thus, light 420 is output from the secondsurface 401-2. In some embodiments, light 420 is transmitted withoutchange in polarization or direction.

As shown in FIG. 4C, reflective polarization sensitive optical diffuser402 includes a first surface 402-1, a second surface 402-2 opposite tofirst surface 402-1, and optically anisotropic molecules disposedbetween the first surface 402-1 and the second surface 402-2. In someembodiments, reflective polarization sensitive optical diffuser 402 isconfigured to output light from the first surface 402-1 in response toreceiving incident light at the first surface 402-1. As shown, when theincident light (e.g., light 410) has the first circular polarization,diffuse light 414 having the first circular polarization is output fromthe first surface 402-1. In some embodiments, the light 410 issubstantially collimated and propagating in a first direction. In someembodiments, reflective polarization sensitive optical diffuser 402 isconfigured to diffuse the light 410 to output diffuse light 414 thatpropagates in a plurality of directions. When the incident light (e.g.,light 420) has the second circular polarization, reflective polarizationsensitive optical diffuser 402 is configured to transmit light 420 fromthe second surface 402-2. In some embodiments, light 420 is transmittedwithout change in polarization or direction.

In some embodiments, a polarization sensitive optical diffuser (e.g.,polarization sensitive optical diffuser 400, transmissive polarizationsensitive optical diffuser 401, reflective polarization sensitiveoptical diffuser 402) may be incident angle selective, and/or to bewavelength selective.

For example, as shown in FIG. 4D, polarization sensitive opticaldiffuser 400, which in this example is a transmissive polarizationsensitive optical diffuser, can be incident angle selective and interactdifferently with incident light having different incident angles withrespect to a direction indicated by dashed line 490 that is normal tofirst surface 400-1. In some embodiments, polarization sensitive opticaldiffuser 400 is configured to diffuse light having the first circularpolarization and incident upon polarization sensitive optical diffuser400 at an incident angle that is within a first predefined incidentangle range (e.g., smaller than angle ϕ). In some embodiments,polarization sensitive optical diffuser 400 is configured to transmitthird light that is incident upon polarization sensitive opticaldiffuser 400 at an incident angle that is outside of the firstpredefined incident angle range (e.g., equal or larger than ϕ),regardless of the polarization of the light.

As shown, light 410 having the first circular polarization can beincident upon polarization sensitive optical diffuser 400 in a directionthat forms a first incident angle θ1 with respect to dashed line 490.First incident angle θ1 is within the first predefined incident anglerange (e.g., θ1<ϕ). Thus, light 410 is diffused at polarizationsensitive optical diffuser 400, and diffuse light 412 having the secondcircular polarization is output from polarization sensitive opticaldiffuser 400 in response to light 410. On the other hand, light 430 isincident upon polarization sensitive optical diffuser 400 at a secondincident angle θ2 that is outside the first predefined incident anglerange (e.g., θ2≥ϕ). Thus, light 430 is transmitted through polarizationsensitive optical diffuser 400 without change in direction orpolarization.

FIG. 4E illustrates wavelength selectivity of polarization sensitiveoptical diffuser 400 in accordance with some embodiments. In someembodiments, polarization sensitive optical diffuser 400 is configuredto diffuse light having the first circular polarization and a wavelengththat is within a first predefined spectral range, and to transmit lighthaving a wavelength that is outside of the first predefined spectralrange regardless of the polarization of the light.

As shown, light 410, having the first circular polarization and a firstwavelength λ1 that is within the first predefined spectral range, isincident upon polarization sensitive optical diffuser 400. Thus, light410 is diffused at polarization sensitive optical diffuser 400 anddiffuse light 412 having the second circular polarization is output frompolarization sensitive optical diffuser 400. On the other hand, light440, which has a wavelength λ that is outside the first predefinedspectral range, is transmitted through polarization sensitive opticaldiffuser 400 without a change in direction or polarization.

Although polarization sensitive optical diffuser 400 is illustrated inFIGS. 4D and 4E as a transmissive polarization sensitive opticaldiffuser (e.g., transmissive polarization sensitive optical diffuser401), it can be understood that descriptions provided above with respectto incident angle selectivity and wavelength selectivity are alsoapplicable to a reflective polarization sensitive optical diffuser(e.g., reflective polarization sensitive optical diffuser 402).

FIG. 5 illustrates a polarization sensitive optical diffuser 500 andoptical paths of light transmitted through polarization sensitiveoptical diffuser 500 in accordance with some embodiments. In someembodiments, as shown in FIG. 5, polarization sensitive optical diffuser500 includes a plurality of optical diffuser layers (e.g., first opticaldiffuser layer 501, second optical diffuser layer 502, and third opticaldiffuser layer 503). First optical diffuser layer 501 has a firstsurface 500-1, a second surface 500-2, and optically anisotropicmolecules 509-1 disposed between first surface 500-1 and second surface500-2. Third optical diffuser layer 503 has a third surface 500-3, afourth surface 500-4, and optically anisotropic molecules 509-3 disposedbetween third surface 500-3 and fourth surface 500-4. Second opticaldiffuser layer 502, has optically anisotropic molecules 509-2 disposedbetween second surface 500-2 and third surface 500-3.

In some embodiments, first optical diffuser layer 501 is configured todiffuse light having a wavelength that is within a first predefinedspectral range, second optical diffuser layer 502 is configured todiffuse light having a wavelength that is within a second predefinedspectral range that is different from the first predefined spectralrange, and third optical diffuser layer 503 is configured to diffuselight having a wavelength that is within a third predefined spectralrange that is different from the first predefined spectral range andfrom the second predefined spectral range. In some embodiments,polarization sensitive optical diffuser 500 is configured to diffuselight having a wavelength that is within a wider spectral range thatencompasses the first predefined spectral range, the second predefinedspectral range, and the third predefined spectral range. As shown ininset A, optically anisotropic molecules 509-1 that are disposed betweenfirst surface 500-1 and second surface 500-2 are arranged such that thefirst optical diffuser layer 501 diffuses light 410 having the firstcircular polarization and a first wavelength λ1 that is within the firstpredefined spectral range. Thus, diffuse light 412 having the firstwavelength λ1 is output from first optical diffuser layer 501 via secondsurface 500-2. Optically anisotropic molecules 509-2 that are disposedbetween second surface 500-2 and third surface 500-3 are arranged suchthat second optical diffuser layer 502 diffuses light 510 having thefirst circular polarization and a second wavelength λ2 that is within asecond predefined spectral range and transmits diffuse light 412 withoutchange in direction or polarization. Thus, diffuse light 512 having thesecond wavelength λ2 is output from second optical diffuser layer 502through third surface 500-3. Optically anisotropic molecules 509-3 thatare disposed between third surface 500-3 and fourth surface 500-4 arearranged such that the third optical diffuser layer diffuses light 520having the first circular polarization and a third wavelength λ3 that iswithin a third predefined spectral range and transmits diffuse light 412and diffuse light 512 without change in direction or polarization. Thus,diffuse light 522 having the third wavelength λ3 is output from fourthsurface 500-4, together with diffuse light 412 and diffuse light 512.Thus, when incident light (e.g., light 410, light 510, or light 520)having the first polarization and wavelengths within the wider spectralrange encompassing the first predefined spectral range, the secondpredefined spectral range, and the third predefined spectral range isincident upon polarization sensitive optical diffuser 500, polarizationsensitive optical diffuser 500 outputs diffuse light (e.g., diffuselight 412, diffuse light 512, or diffuse light 522) having wavelengthscorresponding to the wavelengths of the incident light. Polarizationsensitive optical diffuser 500 is also configured to receive light 530having a wavelength that is outside the wider spectral rangeencompassing the first predefined spectral range, the second predefinedspectral range, and the third predefined spectral range, and transmitthe light 530, without change in polarization or direction, regardlessof the polarization of the light 530. In some embodiments, whenpolarization sensitive optical diffuser 500 is configured to diffuselight having wavelengths within the wider spectral range encompassingthe first predefined spectral range, the second predefined spectralrange, and the third predefined spectral range, it may be desirable todesign the first optical diffuser layer 501, the second optical diffuserlayer 502, and the third optical diffuser layer 503 to diffuse lighthaving a same handedness or polarization.

In some embodiments, polarization sensitive optical diffuser 500 may beconfigured to diffuse light that is incident upon polarization sensitiveoptical diffuser 500 with an incident angle that is within a widerincident angle range encompassing a first predefined incident anglerange, a second predefined incident angle range that is different fromthe first predefined incident angle range, or a third predefinedincident angle range that is different from the first predefinedincident angle range and the second incident angle spectral range. Forexample, optically anisotropic molecules 509-1, disposed between firstsurface 500-1 and second surface 500-2, may be arranged such that thefirst optical diffuser layer diffuses light 410, having the firstcircular polarization and incident upon polarization sensitive opticaldiffuser 500 at first angle θ1 that is within the first predefinedincident angle range, and outputs diffuse light 412. Opticallyanisotropic molecules 509-2, disposed between second surface 500-2 andthird surface 500-3, are arranged such that the second optical diffuserlayer diffuses light 510, having the first circular polarization andincident upon polarization sensitive optical diffuser 500 at a secondangle that is within the second predefined incident angle range, andoutputs diffuse light 512. Optically anisotropic molecules 509-3,disposed between third surface 500-3 and fourth surface 500-4, arearranged such that the third optical diffuser layer diffuses light 520,having the first circular polarization and incident upon polarizationsensitive optical diffuser 500 at a third angle that is within the thirdpredefined incident angle range, and outputs diffuse light 522. Thus,when incident light (e.g., light 410, light 510, light 520) having thefirst polarization and incident upon polarization sensitive opticaldiffuser 500 at an incident angle that is within the wider incidentangle range encompassing the first predefined incident angle range, thesecond predefined incident angle range, or the third predefined incidentangle range, polarization sensitive optical diffuser 500 outputs diffuselight (e.g., diffuse light 412, diffuse light 512, diffuse light 522.Polarization sensitive optical diffuser 500 is also configured toreceive light (e.g., light 540) incident upon polarization sensitiveoptical diffuser 500 at an incident angle that is outside the widerincident angle range encompassing the first predefined incident anglerange, the second predefined incident angle range, and the thirdpredefined incident angle range, and transmit light 540, without changein polarization or direction, regardless of the polarization orwavelength of light 540. In some embodiments, when polarizationsensitive optical diffuser 500 is configured to diffuse light havingwavelengths within the wider spectral range encompassing the firstpredefined incident angle range, the second predefined incident anglerange, and the third predefined incident angle range, it may bedesirable to design the first optical diffuser layer 501, the secondoptical diffuser layer 502, and the third optical diffuser layer 503 todiffuse light having a same handedness.

Although polarization sensitive optical diffuser 500 is shown in FIG. 5to include three optical diffuser layers, it is understood thatpolarization sensitive optical diffuser 500 may include any number ofoptical diffuser layers. Additionally, although polarization sensitiveoptical diffuser 500 is illustrated in as a transmissive polarizationsensitive optical diffuser, it can be understood that descriptionsprovided with respect to FIG. 5 can also be applied to reflectivepolarization sensitive optical diffusers.

In some embodiments, a polarization sensitive optical diffuser may be astandalone optical element (e.g., does not include any substrates), aspreviously shown in FIGS. 4A-4E and 5. Alternatively, a polarizationsensitive optical diffuser may also include one or more opticallytransparent substrates. FIGS. 6A-6C illustrate polarization sensitiveoptical diffusers 600, 602, and 604 each including polarizationsensitive optical diffuser 400 and one or more optically transparentsubstrates 690 and/or 692 in accordance with some embodiments.Polarization sensitive optical diffuser 400 in polarization sensitiveoptical diffusers 600, 602, and 604 include features similar to thosedescribed above with respect to any of FIGS. 4A-4E.

In some embodiments, as shown in FIG. 6A, optically transparentsubstrate 690 is coupled to first surface 400-1. In a second example,polarization sensitive optical diffuser 602, shown in FIG. 6B, includesoptically transparent substrate 692 coupled to the second surface 400-2.In a third example, polarization sensitive optical diffuser 604, shownin FIG. 6C, includes optically transparent substrate 690, coupled tofirst surface 400-1, and optically transparent substrate 692, coupled tosecond surface 400-2.

In some embodiments, one of the one or more optically transparentsubstrates 690, 692 may be a protective layer. Thus, in someembodiments, a polarization sensitive optical diffuser (e.g., such aspolarization sensitive optical diffuser 600, 602, 604) may include aprotective layer on either of the first surface 400-1 or the secondsurface 400-2. For example, substrate 692 may be a protective layer andpolarization sensitive optical diffuser 604 includes substrate 690coupled to the first surface 400-1, and a protective layer (e.g.,substrate 692) coupled to the second surface 400-2.

In some embodiments, polarization sensitive optical diffuser 500 mayinclude one or more optically transparent substrate (e.g., substrates690 and 692) coupled to one or more of the plurality of optical diffuserlayers (e.g., first optical diffuser layer 501, second optical diffuserlayer 502, and third optical diffuser layer 503). For example, at leastone of the first surface 600-1, second surface 600-2, third surface600-3, or fourth surface 600-4 is coupled to optically transparentsubstrate 690 and/or protective layer 692 (e.g., optically transparentsubstrate 692).

In some embodiments, an optical diffuser (e.g., polarization sensitiveoptical diffusers 400, 402, 401, 402, 500, 600, 602, 604) may be apolarization sensitive hologram. In some embodiments, the opticallyanisotropic molecules (e.g., optically anisotropic molecules 409) form apolarization sensitive hologram.

FIG. 7 is a flowchart illustrating a method 700 of diffusing light inaccordance with some embodiments. Method 700 includes (operation 710)receiving incident light 410 at an optical diffuser (e.g., polarizationsensitive optical diffusers 400, 401, 402, 500, 600, 602, 604) thatincludes optically anisotropic molecules 409 arranged in a predefinedconfiguration, and (operation 720) outputting diffuse light (e.g., light412, 414) from the optical diffuser in response to receiving theincident light 410 when the incident light 410 has a first set ofproperties. The first set of properties includes a first polarization(e.g., first circular polarization). The method 700 also includes(operation 730) transmitting the incident light 410 in response toreceiving the incident light 410 when the incident light 410 has asecond set of properties. The second set of properties includes a secondpolarization (e.g., second circular polarization).

In some embodiments, the optical diffuser (e.g., polarization sensitiveoptical diffusers 400, 401, 402, 500, 600, 602, 604) has a first surface(e.g., first surface 400-1, 401-1, 402-1, 500-1) and a second surface(e.g., second surface 400-2, 401-2, 402-2, 500-2) that is opposite tothe first surface, and (operation 712) receiving the incident light 410includes receiving the incident light 410 at the first surface.

In some embodiments, the optical diffuser (e.g., polarization sensitiveoptical diffusers 400, 401, 500) has a first surface (e.g., firstsurface 400-1, 401-1, 500-1) and a second surface (e.g., second surface400-2, 401-2, 500-2) that is opposite to the first surface. The incidentlight 410 is received at the first surface, and (operation 722)outputting the incident light 410 includes outputting the diffuse light412 having the second polarization from the second surface.

In some embodiments, the optical diffuser (e.g., polarization sensitiveoptical diffusers 400, 402) has a first surface (e.g., first surface400-1, 402-1) and a second surface (e.g., second surface 400-2, 402-2)that is opposite to the first surface. The incident light 410 isreceived at the first surface, and (operation 724) outputting theincident light 410 includes outputting the diffuse light 414 having thefirst polarization from the first surface.

In some embodiments, method 700 further includes (operation 714)receiving incident light (e.g., light 410) that is propagating in afirst direction, and (operation 726) outputting the diffuse light (e.g.,diffuse light 412, 414) such that the diffuse light propagates in aplurality of directions.

FIG. 8 is a flowchart illustrating a method 800 of creating apolarization sensitive optical diffuser in accordance with someembodiments. Method 800 includes (step 810) illuminating opticallyanisotropic molecules (e.g., molecules of an alignment layer, bulkliquid crystal material) with directional light (e.g., propagating in afirst direction, substantially collimated light) having firstpolarization (e.g., first circular polarization), and (step 820)concurrently with illuminating the optically anisotropic molecules withdirectional light, illuminating the optically anisotropic molecules withdiffuse light (e.g., propagating in a plurality of directions) havingsecond polarization (e.g., second circular polarization) that isorthogonal to the first polarization.

In some embodiments, a polarization sensitive optical diffuser mayinclude an alignment layer (e.g., a photoalignment layer, a layerincluding organic or inorganic compounds including photosensitivegroups) and helical structures formed by optically anisotropicmolecules. In such cases, the alignment layer is formed by adding alayer of photoalignment material on a surface of the polarizationsensitive optical diffuser. The alignment layer is then exposed toalignment light (e.g., linearly, circularly, or elliptically polarizedlight) with a desired intensity and incident angle. The alignment lightis scanned over the alignment layer while rotating polarization of thealignment light, effectively writing an x-y alignment pattern onto analignment layer in two dimensions. After preparation of the alignmentlayer, a layer of optically anisotropic molecules is applied onto thealignment layer, forming helical structures. The x-y alignment patternof the alignment layer defines the orientation of the helical structuresof the optically anisotropic molecules. After formation of the helicalstructures, the layer of optically anisotropic molecules is firmed(e.g., fixed, set, or cured) to form a polymer. In some embodiments, thefirming includes thermal and/or UV curing. In some embodiments, helicalstructures are formed of liquid crystals, such as cholesteric liquidcrystals. The helical structures are aligned along helical axes. In someembodiments, each of the helical axes are substantially parallel to thez-axis (e.g., each helical axis and the z-axis form an angle less than 1degree). Alternatively, the helical axes may form a non-zero angle withrespect to the z-axis. In some embodiments, the optically anisotropicmolecules are rotated in a same rotational direction (forming a helicaltwist) about a respective helical axis.

In some embodiments, a polarization sensitive optical diffuser does notinclude an alignment layer and the helical structures of thepolarization sensitive optical diffuser are formed without an alignmentlayer.

In some embodiments, a polarization sensitive optical diffuser includesbulk liquid crystal. In such cases, an x-y-z alignment pattern can bewritten in three dimensions in the bulk liquid crystal material.

FIG. 9 is a schematic diagram illustrating a polarization sensitiveoptical diffuser 900, corresponding to any of polarization sensitiveoptical diffusers 400-402, according to some embodiments. Each rod 912is a representation of an orientation of an optically anisotropicmolecule in polarization sensitive optical diffuser 900. Dashed lines916 demarcate transitions between different domains 914-1, 914-2, and914-3. In general, the boundaries can be located anywhere in thepolarization sensitive optical diffuser. In some embodiments, theboundaries are periodic such that the boundaries are spaced apart evenly(e.g., forming a periodic structure of domains). In some embodiments,the orientations of the optically anisotropic molecules in polarizationsensitive optical diffuser 900 follow a mostly periodic pattern alongthe x direction. In some embodiments, the transitions 916 are spacedapart almost evenly and can be located anywhere in the polarizationsensitive optical diffuser 900. Although three domains are shown forillustrative purposes, polarization sensitive optical diffuser 900 mayhave any number of domains.

As shown, optically anisotropic molecules in each domain are aligned toform a grating-like pattern. Thus, in each domain, the opticallyanisotropic molecules are configured to diffract incident light, havinga desired handedness and being within predetermined angular andwavelength ranges, in a specific direction. As shown, the alignment ofthe optically anisotropic molecules vary slightly between two adjacentdomains and thus, optically anisotropic molecules in adjacent domainsare configured to diffract the incident light in different directions,resulting in an overall effect of diffuse light being output from thepolarization sensitive optical diffuser 900. For example, opticallyanisotropic molecules in domain 914-1 may be configured to direct (e.g.,diffract) the incident light in a first direction, optically anisotropicmolecules in domain 914-2 are configured to direct (e.g., diffract) theincident light in a second direction that is different from the firstdirection, and optically anisotropic molecules in domain 914-3 areconfigured to direct (e.g., diffract) the incident light in a thirddirection that is different from each of the first and seconddirections. Thus, the combined effect of diffracting light in slightlydifferent directions at different domains of polarization sensitiveoptical diffuser 900 results in the incident light being diffused andoutput as diffuse light. Additionally, just as an optical grating can bedesigned to redirect light at a predetermined direction (e.g.,predetermined angle), polarization sensitive optical diffuser 900 canalso be designed to output diffuse light such that a chief ray of theoutput diffuse light propagates in a predetermined direction (e.g.,forms a predetermined angle with respect to a surface of polarizationsensitive optical diffuser 900).

In light of these principles, we now turn to certain embodiments of apolarization sensitive optical diffuser (e.g., polarization sensitiveoptical diffusers 400, 401, 402, 500, 502, 504, 500).

In accordance with some embodiments, an optical diffuser (e.g.,polarization sensitive optical diffusers 400, 401, 402, 500, 600, 602,604) includes optically anisotropic molecules (e.g., opticallyanisotropic molecules 409) that are arranged in a predefinedconfiguration such that the optical diffuser outputs diffuse light(e.g., light 412, 414) upon receiving first light (e.g., light 410)having a first polarization (e.g., first circular polarization) andtransmits second light (e.g., light 420) having a second polarization(e.g., second circular polarization) that is different from (e.g.,orthogonal to) the first polarization upon receiving the second light.

In some embodiments, the optical diffuser (e.g., polarization sensitiveoptical diffuser 401) includes a first surface (e.g., first surface401-1), a second surface (e.g., second surface 401-2) that is oppositeto the first surface. The optical diffuser is configured to receive thefirst light (e.g., light 410) at the first surface (e.g., first surface401-1) and to output the diffuse light (e.g., diffuse light 412) fromthe second surface (e.g., second surface 401-2). The diffuse light hasthe second polarization (e.g., second circular polarization).

In some embodiments, the optical diffuser (e.g., polarization sensitiveoptical diffuser 402) includes a first surface (e.g., first surface402-1), a second surface (e.g., second surface 402-2) that is oppositeto the first surface. The optical diffuser is configured to receive thefirst light (e.g., light 410) at the first surface (e.g., first surface402-1) and to output the diffuse light (e.g., diffuse light 414) fromthe first surface. The diffuse light has the first polarization (e.g.,first circular polarization).

In some embodiments, the optical diffuser (e.g., polarization sensitiveoptical diffusers 400, 401, 402, 500, 600, 602, 604) is configured toreceive the first light (e.g., light 410) propagating in a firstdirection (e.g. the first light is substantially collimated) and todiffuse the first light such that the diffuse light propagates in aplurality of directions.

In some embodiments, the optical diffuser (e.g., polarization sensitiveoptical diffusers 400, 401, 402, 500) includes a first surface (e.g.,first surface 400-1, 401-1, 402-1, 500-1), a second surface (e.g.,second surface 400-2, 401-2, 402-2, 500-2) that is opposite to the firstsurface. The first light (e.g., light 410) is incident upon the firstsurface (e.g., first surface 400-1, 401-1, 402-1, 500-1) at an incidentangle (e.g., first incident angle θ1) that is within a first predefinedincident angle range (e.g., first predefined incident angle range ϕ).The optical diffuser is further configured to transmit third light(e.g., light 430) that is incident upon either the first surface or thesecond surface (e.g., second surface 400-2, 401-2, 402-2, 500-2) at anangle that is outside of the first predefined incident angle range.

In some embodiments, the first light (e.g., light 410) has a firstwavelength (e.g., first wavelength λ1) that is within a first predefinedspectral range. The optical diffuser is further configured to transmitfourth light (e.g., light 440) having wavelength that is outside of thepredefined spectral range, regardless of the polarization of the fourthlight.

In some embodiments, the first light (e.g., light 410) has a firstwavelength (e.g., first wavelength λ1) that is within a first predefinedspectral range. In some embodiments, the optical diffuser (e.g., opticaldiffuser 500) further includes a third surface (e.g., third surface500-3) that is located proximate to (e.g., close to, in proximity to)the second surface (e.g., second surface 500-2). The opticallyanisotropic molecules are disposed between the second surface and thethird surface, and arranged such that the optical diffuser diffusesfifth light (e.g., fifth light 510) as well as the first light andtransmits sixth light (e.g., sixth light 530) as well as the secondlight (e.g., second light 520). The fifth light has the firstpolarization and a second wavelength (e.g., second wavelength λ2) thatis within a second predefined spectral range that is different from thefirst predefined spectral range. The sixth light has a wavelengthoutside of the first spectral range and the second spectral range. Theoptical diffuser is configured to transmit the sixth light regardless ofthe polarization of the sixth light.

In some embodiments, the first light (e.g., light 410) is incident uponthe optical diffuser (e.g., polarization sensitive optical diffuser 500)at a first incident angle (e.g., first incident angle θ1) that is withina first predefined incident angle range (e.g., first predefined incidentangle range ϕ). In some embodiments, the optical diffuser furtherincludes a fourth surface (e.g., third surface 500-3) that is locatedproximate to (e.g., close to, in proximity to) the second surface (e.g.,second surface 500-2). The optically anisotropic molecules are disposedbetween the second surface and the fourth surface, and arranged suchthat the optical diffuser diffuses seventh light as well as the firstlight and transmits eighth light as well as the second light (e.g.,second light 520). The seventh light has the first polarization and isincident upon the optical diffuser at a second incident angle that iswithin a second predefined incident angle range that is different fromthe first predefined incident angle range. The eighth light has awavelength outside of the first incident angle range and the secondincident angle range. The optical diffuser is configured to transmit theeighth light regardless of the polarization of the eighth light.

In some embodiments, the optically anisotropic molecules (e.g.,optically anisotropic molecules 409) form a polarization sensitivehologram.

In some embodiments, the optical diffuser (e.g., polarization sensitiveoptical diffusers 500, 600, 602, 604) includes one or more opticallytransparent substrates (e.g., first optically transparent substrate 590,second optically transparent substrate 592). The optical diffuser has afirst surface and a second surface opposite to the first surface (e.g.,first surface 400-1, 401-1, 402-1, 500-1) and a second surface (e.g.,second surface 400-2, 401-2, 402-2, 500-2) and at least one of the firstsurface and the second surface is coupled to one of the one or moreoptically transparent substrates. For example, first surface 400-1 maybe coupled to first optically transparent substrate 590 and/or secondsurface 400-2 may be coupled to second optically transparent substrate592. In some embodiments, when the optical diffuser has one or moresurfaces in addition to the first surface and the second surface, theoptical diffuser may include one or more optically transparentsubstrates such that at least two surfaces are coupled to opposite sidesof a same optically transparent substrate. For example, polarizationsensitive optical diffuser 500 may include an optically transparentsubstrate located between and coupled to first surface 400-1 and secondsurface 400-2.

In some embodiments, the optical diffuser (e.g., polarization sensitiveoptical diffuser 500) has a first surface (e.g., first surface 400-1,401-1, 402-1, 500-1) and a second surface (e.g., second surface 400-2,401-2, 402-2, 500-2) that is opposite to the first surface. The opticaldiffuser includes a protective layer on either the first surface of thesecond surface. For example, the second optical diffuser layer 502 mayinclude first optically transparent substrate 590 and second opticallytransparent substrate 592 and second optically transparent substrate 592may be a protective layer.

In some embodiments, the optical diffuser (e.g., polarization sensitiveoptical diffusers 500, 600, 602, 604) has a first surface (e.g., firstsurface 400-1, 401-1, 402-1, 500-1) and a second surface (e.g., secondsurface 400-2, 401-2, 402-2, 500-2) that is opposite to the firstsurface. The optical diffuser includes one or more photoalignment layers(e.g., photoalignment layers) and at least one of the first surface andthe second surface is coupled to one of the one or more photoalignmentlayers.

In some embodiments, the optically anisotropic molecules (e.g.,optically anisotropic molecules 409) are arranged in a helicalconfiguration.

In some embodiments, the optically anisotropic molecules (e.g.,optically anisotropic molecules 409 include a chiral dopant.

In some embodiments, the optically anisotropic molecules are arranged ina plurality of domains. Each domain of the plurality of domains includesa portion of the optically anisotropic molecules forming a grating-likepattern. Portions of optically anisotropic molecules in adjacent domainsare configured to diffract the first light in different directions.

In accordance with some embodiments, a method (e.g., method 700) fordiffusing light includes (operation 710) receiving incident light (e.g.,light 410) at an optical diffuser (e.g., polarization sensitive opticaldiffusers 400, 401, 402, 500, 600, 602, 604) that includes opticallyanisotropic molecules (e.g., optically anisotropic molecules 409). Themethod also includes (operation 720) outputting diffuse light (e.g.,diffuse light 412, 414) from the optical diffuser in response toreceiving the incident light when the incident light has a first set ofproperties. The first set of properties include a first polarization(e.g., first circular polarization). The method also includes (operation730) transmitting the incident light in response to receiving theincident light when the incident light has a second set of properties.The second set of properties include a second polarization (e.g., secondcircular polarization) that is different from (e.g., orthogonal to) thefirst polarization.

In some embodiments, the optical diffuser (e.g., polarization sensitiveoptical diffusers 400, 401, 500) includes a first surface (e.g., firstsurface 400-1, 401-1, 500-1) and a second surface (e.g., second surface400-2, 401-2, 500-2) that is opposite to the first surface. Receivingthe incident light (e.g., incident light 410) includes (operation 712)receiving the incident light at the first surface, and outputtingdiffuse light includes (operation 722) outputting diffuse light (e.g.,diffuse light 414) having the second polarization from the secondsurface (e.g., second surface 400-2, 401-2, 500-2).

In some embodiments, the optical diffuser (e.g., polarization sensitiveoptical diffusers 400, 402, 500) includes a first surface (e.g., firstsurface 400-1, 402-1, 500-1) and a second surface (e.g., second surface400-2, 402-2, 500-2) that is opposite to the first surface. Receivingthe incident light (e.g., incident light 410) includes (operation 712)receiving the incident light at the first surface, and outputtingdiffuse includes (operation 724) outputting diffuse light (e.g., diffuselight 412) having the first polarization from the first surface (e.g.,first surface 400-1, 402-1, 500-1).

In some embodiments, receiving the incident light (e.g., light 410)includes (operation 714) receiving incident light that is propagating ina first direction and outputting diffuse light (e.g., diffuse light 412,414) includes (operation 726) diffusing the first light such that thediffuse light propagates in a plurality of directions.

In accordance with some embodiments, a method (e.g., method 800) ofmaking an optical diffuser (e.g., polarization sensitive opticaldiffusers 400, 401, 402, 500, 600, 602, 604) includes (step 810)illuminating optically anisotropic molecules with directional light(e.g., propagating in a first direction, substantially collimated light)having a first polarization (e.g., first circular polarization), and(step 820) concurrently with illuminating optically anisotropicmolecules with the directional light, illuminating optically anisotropicmolecules with diffuse light (e.g., propagating in a plurality ofdirections) having a second polarization (e.g., second circularpolarization) that is different from (e.g., orthogonal to) the firstpolarization.

Although various drawings illustrate operations of particular componentsor particular groups of components with respect to one eye, a personhaving ordinary skill in the art would understand that analogousoperations can be performed with respect to the other eye or both eyes.For brevity, such details are not repeated herein.

Although some of various drawings illustrate a number of logical stagesin a particular order, stages which are not order dependent may bereordered and other stages may be combined or broken out. While somereordering or other groupings are specifically mentioned, others will beapparent to those of ordinary skill in the art, so the ordering andgroupings presented herein are not an exhaustive list of alternatives.Moreover, it should be recognized that the stages could be implementedin hardware, firmware, software or any combination thereof.

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit the scope of the claims to the precise forms disclosed. Manymodifications and variations are possible in view of the aboveteachings. The embodiments were chosen in order to best explain theprinciples underlying the claims and their practical applications, tothereby enable others skilled in the art to best use the embodimentswith various modifications as are suited to the particular usescontemplated.

What is claimed is:
 1. An optical diffuser, comprising: opticallyanisotropic molecules arranged in a predefined configuration such thatthe optical diffuser outputs diffuse light upon receiving first lighthaving a first polarization and transmits second light having a secondpolarization that is different from the first polarization uponreceiving the second light, wherein: the first light has a wavelengthwithin a first predefined spectral range; and the optical diffuser isfurther configured to transmit fourth light having wavelength outside ofthe first predefined spectral range regardless of a polarization of thefourth light.
 2. The optical diffuser of claim 1, wherein the opticaldiffuser has a first surface and a second surface opposite to the firstsurface, and the optical diffuser is configured to: receive the firstlight at the first surface; and output the diffuse light from the secondsurface, the diffuse light having the second polarization.
 3. Theoptical diffuser of claim 1, wherein the optical diffuser has a firstsurface and a second surface opposite to the first surface, and theoptical diffuser is configured to: receive the first light at the firstsurface; and output the diffuse light from the first surface, thediffuse light having the first polarization.
 4. The optical diffuser ofclaim 1, wherein the optical diffuser is configured to receive the firstlight propagating in a first direction and to diffuse the first lightsuch that the diffuse light propagates in a plurality of directions. 5.The optical diffuser of claim 2, further comprising: a third surfaceproximate to the second surface; and optically anisotropic moleculesdisposed between the second surface and the third surface and arrangedsuch that the optical diffuser diffuses fifth light as well as the firstlight and transmits sixth light as well as the second light, wherein thefifth light has the first polarization and a wavelength within a secondpredefined spectral range that is different from the first predefinedspectral range; the sixth light has a wavelength outside of the firstpredefined spectral range and the second predefined spectral range; andthe optical diffuser is configured to transmit the sixth lightregardless of a polarization of the sixth light.
 6. The optical diffuserof claim 1, further comprising one or more optically transparentsubstrates, wherein the optical diffuser has a first surface and asecond surface opposite to the first surface, and at least one of thefirst surface and the second surface is coupled to one of the one ormore optically transparent substrate.
 7. The optical diffuser of claim1, wherein the optical diffuser has a first surface and a second surfaceopposite to the first surface, and the optical diffuser further includesa protective layer on either of the first surface or the second surface.8. The optical diffuser of claim 1, wherein the optical diffuser has afirst surface and a second surface opposite to the first surface, andthe optical diffuser further includes one or more photoalignment layers,wherein at least one of the first surface and the second surface iscoupled to one of the one or more photoalignment layers.
 9. The opticaldiffuser of claim 1, wherein the optically anisotropic molecules arearranged in a helical configuration.
 10. The optical diffuser of claim1, wherein the optically anisotropic molecules include a chiral dopant.11. The optical diffuser of claim 1, wherein: the optically anisotropicmolecules are arranged in a plurality of domains, each of the pluralityof domains including a portion of the optically anisotropic moleculesforming a grating-like pattern; and portions of optically anisotropicmolecules in adjacent domains are configured to diffract the first lightin different directions.
 12. A method of diffusing light, the methodcomprising: receiving incident light at the optical diffuser of claim 1,including optically anisotropic molecules arranged in a predefinedconfiguration; outputting diffuse light from the optical diffuser inresponse to receiving the incident light when the incident light has afirst set of properties, wherein the first set of properties includes afirst polarization; and transmitting the incident light in response toreceiving the incident light when the incident light has a second set ofproperties, wherein the second set of properties includes a secondpolarization that is different from the first polarization.
 13. Themethod of claim 12, wherein the optical diffuser has a first surface anda second surface opposite to the first surface, receiving incident lightincludes receiving the incident light at the first surface, andoutputting diffuse light includes outputting, from the second surface,diffuse light having the second polarization.
 14. The method of claim12, wherein the optical diffuser has a first surface and a secondsurface opposite to the first surface, receiving incident light includesreceiving the incident light at the first surface, and outputtingdiffuse light includes outputting, from the first surface, diffuse lighthaving the first polarization.
 15. The method of claim 12, wherein:receiving the incident light includes receiving the incident light thatis propagating in a first direction; and outputting diffuse lightincludes diffusing the incident light such that the diffuse lightpropagates in a plurality of directions.
 16. An optical diffuser,comprising: optically anisotropic molecules arranged in a predefinedconfiguration such that the optical diffuser outputs diffuse light uponreceiving first light having a first polarization and transmits secondlight having a second polarization that is different from the firstpolarization upon receiving the second light, wherein: the opticaldiffuser has a first surface and a second surface opposite to the firstsurface; the first light is incident upon the first surface at anincident angle within a first predefined incident angle range; and theoptical diffuser is further configured to transmit third light that isincident upon either the first surface or the second surface at an anglethat is outside of the first predefined incident angle range.
 17. Theoptical diffuser of claim 16, further comprising: a fourth surfaceproximate to the second surface; and optically anisotropic molecules,disposed between the second surface and the fourth surface, arrangedsuch that the optical diffuser diffuses seventh light as well as thefirst light and transmits eighth light as well as the second light,wherein the seventh light an incident angle wavelength within a secondpredefined incident angle range that is different from the firstpredefined incident angle range; the eighth light has an incident angleoutside of the first predefined incident angle range and the secondpredefined incident angle range; and the optical diffuser is configuredto transmit the eighth light regardless of a polarization of the eighthlight.
 18. An optical diffuser, comprising: optically anisotropicmolecules arranged in a predefined configuration such that the opticaldiffuser outputs diffuse light upon receiving first light having a firstpolarization and transmits second light having a second polarizationthat is different from the first polarization upon receiving the secondlight, wherein the optically anisotropic molecules form a polarizationsensitive hologram.
 19. A method of making an optical diffuser, themethod comprising: illuminating optically anisotropic molecules withdirectional light having a first polarization; and concurrently withilluminating the optically anisotropic molecules with the directionallight, illuminating the optically anisotropic molecules with diffuselight having a second polarization that is different from the firstpolarization.